Cross-reference to Related Applications
Technical Field
[0002] The present disclosure relates, generally, to an accessory for a continuous belt
screen assembly and, more particularly, to a flow restrictor for a continuous belt
screen assembly, to a continuous belt screen assembly including the flow restrictor
and to a method of controlling flow through a continuous belt screen assembly.
Background
[0003] Continuous belt screen assemblies are used in wastewater management to remove solids
and other debris from wastewater. The wastewater flows into the assembly, is screened
by a moving belt screen, and exits from outlets arranged at one or both downstream
sides of the assembly. The flow of wastewater in this way exerts torsional forces
on the assembly which can cause material fatigue and, consequently, affect functionality
of the assembly such that the assembly requires downtime for maintenance.
[0004] Any discussion of documents, acts, materials, devices, articles or the like which
has been included in the present specification is not to be taken as an admission
that any or all of these matters form part of the prior art base or were common general
knowledge in the field relevant to the present disclosure as it existed before the
priority date of each of the appended claims.
Summary
[0005] According to some disclosed embodiments, there is provided a flow restrictor for
a continuous belt screen assembly having a base, opposed sides, an inlet and at least
one outlet, the assembly, in use, being arranged in a channel having a pair of opposed
walls and containing a liquid, the flow restrictor comprising: a body mountable to
a downstream end of the assembly to restrict the liquid flowing out of the at least
one outlet, the body defining at least a portion of at least one aperture configured
to control a level of the liquid upstream of the body.
[0006] The body may be mountable to define the at least one aperture between the body and
at least one of the walls of the channel.
[0007] The body may comprise two parts which are mountable to be spaced from each other
and extend outwardly from the opposed sides of the assembly. The two parts may be
mirror images of each other. The two parts may be mountable to extend perpendicularly
to the opposed sides. The two parts may be interconnected by a bridging portion.
[0008] The body may be mountable to define a pair of laterally spaced apertures, each aperture
being defined between the body and one of the walls of the channel. Each aperture
may increase in width with increasing distance from the base.
[0009] The at least one aperture may be at least partially defined by at least one straight
line. In addition, or instead, the at least one aperture may be at least partially
defined by at least one curve.
[0010] According to other disclosed embodiments, there is provided a continuous belt screen
assembly including a flow restrictor as described above.
[0011] According to further disclosed embodiments, there is provided a method of controlling
flow through a continuous belt screen assembly, the continuous belt screen assembly
having a base, opposed sides, an inlet and at least one outlet, the assembly, in use,
being arranged in a channel having a pair of opposed walls and containing a liquid,
and the method comprising restricting flow downstream of the continuous belt screen
assembly by at least partially occluding a flow path at a downstream end of the continuous
belt screen assembly to reduce a flow rate differential between fluid flow at the
inlet of the continuous belt screen assembly and fluid flow at the at least one outlet
of the continuous belt screen assembly.
[0012] The at least partially occluding the flow path at the downstream end of the continuous
belt screen assembly may comprise mounting the flow restrictor as described in the
first disclosed embodiment above at the downstream end of the continuous belt screen
assembly.
[0013] Throughout this specification the word "comprise", or variations such as "comprises"
or "comprising", will be understood to imply the inclusion of a stated element, integer
or step, or group of elements, integers or steps, but not the exclusion of any other
element, integer or step, or group of elements, integers or steps.
Brief Description of Drawings
[0014] Embodiments of the disclosure will now be described by way of example only with reference
to the accompany drawings in which:
Figure 1 shows a perspective view of a first embodiment of a flow restrictor mounted
to a downstream end of a continuous belt screen assembly;
Figures 2 shows an end view of the first embodiment of the flow restrictor mounted
to the continuous belt screen assembly shown in Figure 1;
Figure 3 shows an end view of a second embodiment of a flow restrictor mounted to
the continuous belt screen assembly shown in Figure 1;
Figure 4 shows an end view of a third embodiment of a flow restrictor mounted to the
continuous belt screen assembly shown in Figure 1;
Figure 5 shows an end view of a fourth embodiment of a flow restrictor mounted to
the continuous belt screen assembly shown in Figure 1; and
Figure 6 shows an end view of a fifth embodiment of a flow restrictor mounted to the
continuous belt screen assembly shown in Figure 1.
Detailed Description of Exemplary Embodiments
[0015] In the drawings, reference numeral 10 generally designates a flow restrictor 10 for
a continuous belt screen assembly 14 having a base 16, opposed sides 18, 20, an inlet
19 and outlets 40, 43. The assembly 14, in use, is arranged in a channel 38 having
a pair of opposed walls 39, 41 and containing a liquid (not shown). The flow restrictor
10 comprises a body 22 mountable to a downstream end of the assembly 14 to restrict
the liquid flowing out of the outlet 40, 43. The body 22 defines at least a portion
23 of at least one aperture 48, 50 configured to control a level of the liquid upstream
of the body 22.
[0016] In the embodiments illustrated in Figures 1-6, the body 22 of the flow restrictor
10 is mountable to define a pair of laterally spaced apertures 48, 50 defined between
the body 22 and the channel 38. The apertures 48, 50 are at least partially defined
by at least one straight line and/or at least one curve. It will be appreciated that,
in other embodiments, at least one of the apertures 48, 50 may be fully defined by
the body 22 (i.e. the body 22 contains at least one of the apertures 48, 50).
[0017] The body 22 comprises two parts, in the form of plates 24, 26, which are mirror images
of each other. In an embodiment, the plates 24, 26 are mountable in the same plane
but spaced from each other to extend outwardly from the opposed sides 18, 20 of the
continuous belt screen assembly 14. The plates 24, 26 are shown as separate from each
other and secured to the assembly 14.
[0018] However, it will be appreciated that, in other embodiments, the plates 24, 26 may
be connected to each other, for example, by brace members (not shown) to enhance rigidity,
and the connected plates 24, 26 mounted to the assembly 14. Similarly, the plates
24, 26 may include additional structures (not shown) at a downstream side of the plates
24, 26 to enhance rigidity such as a bridging portion 27 interconnecting the plates
24, 26. The bridging portion 27 may be formed integrally or may be secured (bolted)
to the downstream end of the assembly 14, with the plates 24, 26 also being individually
secured (bolted) to the downstream end of the assembly 14. It will also be appreciated
that, in another embodiment, the plates 24, 26 may be mountable to diverge away from
each other in a downstream direction from the continuous belt screen assembly 14.
[0019] It will also be appreciated that, in still another embodiment, the body 22 may be
configured to be a unitary structure which is mountable to extend laterally outwardly
from a downstream end of the assembly 14 to restrict liquid flow in the same way.
[0020] In the figures, the continuous belt screen assembly 14 is shown in a typical use
environment, being installed in a channel 38 defined by opposed side walls 39, 41.
The channel 38 contains water to be treated, such as wastewater, (not illustrated)
which flows into and is screened by a moving belt screen 11 of the assembly 14 before
exiting from two outlets 40, 43 of the assembly 14. The belt screen 11 generally moves
continuously in a single direction. The assembly 14 is secured to a top surface 46
of the walls 39, 41 of the channel 38 by a pair of mounting brackets 42, 44. The liquid
level upstream of the assembly 14 is typically higher than the liquid level downstream
of the assembly 14 which can contribute to potentially damaging torsional forces being
exerted on the assembly 14 by the liquid.
[0021] The flow restrictor 10 is mountable downstream of the continuous belt screen assembly
14 to control liquid flowing from the outlets 40, 43. In the illustrated embodiments,
the plates 24, 26 are mounted to a downstream end of the assembly 14 by being connected
to the sides 18, 20 of the assembly 14 by fixings, such as bolts, rivets, welds, or
the like. The plates 24, 26 are configured to restrict the fluid flowing out of the
outlet, while the apertures 48, 50 are configured to control a level of the liquid
upstream of the plates 24, 26. The arrangement of the plates 24, 26 in this way causes
the level of liquid upstream of the plates 24, 26 to rise, advantageously reducing
the difference between the liquid level at the outlets 40, 43 of the assembly 14 and
the liquid level upstream of the assembly 14.
[0022] In the illustrated embodiments, the plates 24, 26 are shown as mirror-images of each
other to define symmetrical openings 48, 50. It will be appreciated that the body
22 of the flow restrictor 10 may be alternatively configured to define asymmetrical
openings 48, 50, for example, to compensate for the direction of movement of the belt
screen 11.
[0023] In another embodiment (not shown), the body 22 of the flow restrictor 10 may be mounted
to project from the side walls 39, 41 into the channel 38 to define the laterally
spaced apertures 48, 50 between the body 22 and the sides 18, 20 of the continuous
belt screen assembly 14.
[0024] Each of the laterally spaced apertures 48, 50 increases in width with increasing
distance from the base 16 of the continuous belt screen assembly 14. The configuration
of the apertures 48, 50 defined in part by the flow restrictor 10, allows for the
liquid level upstream (not shown) from the flow restrictor 10 to be controlled, as
discussed in greater detail below.
[0025] Each plate 24, 26 defines a peripheral operative edge 28 across which the liquid
flows. In the illustrated embodiments, each aperture 48, 50 is defined between the
operative edge 28 of one of the plates 24, 26 and the associated side wall 39, 41
of the channel 38.
[0026] As discussed in greater detail below, each operative edge 28 is defined by at least
one straight line or at least one curve. It will be appreciated that the edge 28 may,
instead, be defined by a combination of lines and curves.
[0027] The plates 24, 26 are configured to be mounted such that each operative edge 28 extends
from the base 16 in a direction towards the associated side 18, 20 of the assembly
14. This means that each plate 24, 26 has at least a portion which defines a width
which decreases relative to distance away from the base 16.
[0028] In the embodiment shown in Figures 1 and 2, the plates 24, 26 are configured such
that each operative edge 28 is formed from a compound curve 32, whereby the curve
32 defines a variable gradient.
[0029] In the embodiment shown in Figure 3, the plates 24, 26 are configured such that each
operative edge 28 defines a straight line 30 defining a first, constant gradient.
[0030] In the embodiment shown in Figure 4, the plates 24, 26 are configured such that each
operative edge 28 defines of a first, vertical rectilinear portion 31 extending from
the base 16 to define a gap 29 between each plate 24, 26 and the associated side wall
41, 39 of the channel. Each operative edge 28 further defines a second rectilinear
portion 37 extending from the upper end of the portion 31 and converging towards the
side 18, 20 of the assembly 14. The position of the portion 31 relative to the base
16, and the gradient of the portion 37 of the operative edge 28, affect the liquid
level upstream of the plates 24, 26. Each gap 29 is dimensioned to inhibit free flow
of liquid through it.
[0031] In the embodiment shown in Figure 5, the plates 24, 26 are configured such that each
operative edge 28 defines a convex single curve 33 converging from the base towards
the sides 18, 20 of the assembly 14.
[0032] In the embodiment shown in Figure 6, the plates 24, 26 are configured such that each
operative edge 28 comprises a plurality of facets 34, 35, 36 defining three different
gradients but generally converging towards the sides 18, 20 of the assembly 14.
[0033] In use, the flow restrictor 10 is mounted downstream of the continuous belt screen
assembly 14 installed in the channel 38. The flow restrictor 10 is configured so that,
when mounted in the downstream position, it occludes liquid flowing out of the outlets
40, 43 of the assembly 14 and along the channel 38. The plates 24, 26 of the flow
restrictor 10 are releasably or fixedly secured to the sides 18, 20, respectively,
of the assembly 14. Liquid introduced into the channel 38 upstream of the assembly
14 is screened by the band screen 11 and flows out of the outlets 40, 43. The liquid
then encounters the plates 24, 26 which cause a damming effect to restrict flow, causing
the liquid level to rise upstream of the plates 24, 26.
[0034] It will be appreciated that, alternatively, the continuous belt screen assembly 14
may be provided with the body 22 of the flow restrictor 10 being integrally formed
to extend from either side of the assembly 14 (not shown). When this embodiment is
installed in the channel 38 and liquid flows, as described above, the body 22 causes
the damming effect, thereby controlling the liquid level upstream of the body 22.
[0035] The body 22 of the flow restrictor 10 is configured to be mounted downstream of the
continuous belt screen assembly 14 and have at least a portion which defines a width
which increases relative to increasing distance away from the base 16 of the assembly
14. This means that the body 22 effectively defines a tapered surface arranged to
restrict flow of liquid downstream of the assembly 14. The arrangement of the body
22 in this way advantageously causes the liquid level to rise upstream of the body
22. This control of the liquid level allows the liquid level upstream of the body
22 to be adjusted to be within an acceptable range of the liquid level upstream of
the assembly 14, thereby reducing torsional forces exerted on components of the assembly
14 by the liquid. Further, this control contributes to reducing the average flow velocity
through the channel 38 upstream of the assembly 14, which aids uniform flow through
the belt 11 of the assembly 14, thereby increasing the overall flow capacity of the
assembly 14.
[0036] Advantageously, the damming effect of the flow restrictor 10 on the assembly 14 allows
for a greater overall submergence of the belt 11, which, in turn, increases the flow
through the assembly 14. Increasing the overall submergence of the belt 11 also decreases
the flow velocity through the belt 11, which increases the potential of the belt 11
to capture more solids (i.e. less potential for solid entrainment through the belt
11). This decreased flow velocity through the belt 11 also reduces the pinning effect
of solids on the panels of the assembly 14, which allows for easier and more effective
cleaning by the cleaning system within the assembly 14, which, in turn, assists to
maintain flow capacity of the assembly 14. Without this effect, the flow capacity
would decrease over time as the panels become more difficult to clean. The damming
effect also encourages a more uniform flow across the belt 11, since, without the
damming, the liquid will preferentially flow to the side of the belt travelling downwards
into the channel 38 (i.e. the cleaner side of the belt 11).
[0037] It will be appreciated by persons skilled in the art that numerous variations and/or
modifications may be made to the above-described embodiments, without departing from
the broad general scope of the present disclosure. The present embodiments are, therefore,
to be considered in all respects as illustrative and not restrictive.
1. A flow restrictor for a continuous belt screen assembly having a base, opposed sides,
an inlet and at least one outlet, the assembly, in use, being arranged in a channel
having a pair of opposed walls and containing a liquid, the flow restrictor comprising:
a body mountable to a downstream end of the assembly to restrict the liquid flowing
out of the at least one outlet, the body defining at least a portion of at least one
aperture configured to control a level of the liquid upstream of the body.
2. The flow restrictor according to claim 1, wherein the body is mountable to define
the at least one aperture between the body and at least one of the walls of the channel.
3. The flow restrictor according to claim 1 or claim 2, wherein the body comprises two
parts mountable to be spaced from each other and extend outwardly from the opposed
sides of the assembly.
4. The flow restrictor according to claim 3, wherein the two parts are mountable to extend
perpendicularly to the opposed sides.
5. The flow restrictor according to claim 3 or claim 4, wherein the two parts are interconnected
by a bridging portion.
6. The flow restrictor according to any one of claims 3 to 5, wherein the two parts are
mirror images of each other.
7. The flow restrictor according to any one of the preceding claims, wherein the body
is mountable to define a pair of laterally spaced apertures, each aperture being defined
between the body and one of the walls of the channel.
8. The flow restrictor according to claim 7, wherein each aperture increases in width
with increasing distance from the base.
9. The flow restrictor according to any one of the preceding claims, wherein the at least
one aperture is at least partially defined by at least one straight line.
10. The flow restrictor according to any one of claims 1 to 8, wherein the at least one
aperture is at least partially defined by at least one curve.
11. A continuous belt screen assembly comprising a flow restrictor as claimed in any one
of the preceding claims.
12. A method of controlling flow through a continuous belt screen assembly, the continuous
belt screen assembly having a base, opposed sides, an inlet and at least one outlet,
the assembly, in use, being arranged in a channel having a pair of opposed walls and
containing a liquid, and the method comprising restricting flow downstream of the
continuous belt screen assembly by at least partially occluding a flow path at a downstream
end of the continuous belt screen assembly to reduce a flow rate differential between
fluid flow at the inlet of the continuous belt screen assembly and fluid flow at the
at least one outlet of the continuous belt screen assembly.
13. The method according to claim 12, wherein the at least partially occluding the flow
path at the downstream end of the continuous belt screen assembly comprises mounting
the flow restrictor according to any one of claims 1 to 10 at the downstream end of
the continuous belt screen assembly.